Touch sensor and display device including the same

ABSTRACT

A touch sensor includes: a plurality of sensor pixels; a sensor scan driver for supplying sensor scan signals to the sensor pixels through sensor scan lines; a power supply unit for supplying common voltages to the sensor pixels through common lines; and a read-out circuit connected to the sensor pixels through the common lines, the read-out circuit configured to sense a touch by using an output signal output through the common lines, wherein two sensor pixels adjacent to each other among the sensor pixels share one common line.

RELATED APPLICATIONS

The present application claims priority to Korean Patent Application No.10-2017-0064114, filed on May 24, 2017, in the Korean IntellectualProperty Office, the entire disclosure of which is incorporated byreference herein.

BACKGROUND 1. Field

An aspect of the present disclosure relates to a touch sensor and adisplay device including the same.

2. Description of the Related Art

Various recognition methods including an optical method, a thermalsensing method, a capacitive method, and the like are known as methodsfor implementing a touch sensor. Among these methods, a capacitive touchsensor senses a point at which capacitance is changed as a hand of auser or an object is in contact therewith, thereby detecting a touchposition. Since the capacitive touch sensor easily senses a multi-touchand has excellent accuracy, the capacitive touch sensor has recentlybeen widely used.

Recently, various functions have been provided to users by detecting notonly touch positions but also fingerprints and touch pressures, usingtouch sensors.

A capacitive fingerprint sensor acquires a shape of a fingerprint (afingerprint pattern) by detecting changes in capacitance depending onshapes of the ridges and valleys in a fingerprint when a surface of ahuman finger comes into contact with a conductive sensing electrode.

SUMMARY

Embodiments provide a miniaturized and integrated touch sensor for touchand fingerprint sensing and a display device including the touch sensor.

According to an aspect of the present disclosure, there is provided atouch sensor including: a plurality of sensor pixels; a sensor scandriver configured to supply sensor scan signals to the sensor pixelsthrough sensor scan lines; a power supply unit configured to supplycommon voltages to the sensor pixels through common lines; and aread-out circuit connected to the sensor pixels through the commonlines, the read-out circuit configured to sense a touch by using anoutput signal output through the common lines, wherein two sensor pixelsadjacent to each other among the sensor pixels share one common line.

One sensor pixel between the two sensor pixels may provide the outputsignal to the read-out circuit during only a first period in one frameperiod, and the other sensor pixel between the two sensor pixels mayprovide the output signal to the read-out circuit during only a secondperiod different from the first period in the one frame period.

The power supply unit may alternately provide a first common voltage anda second common voltage having a level lower than that of the firstcommon voltage to each of the common lines for every certain period.

The power supply unit may simultaneously provide the common voltageshaving levels different from each other to odd-numbered common lines andeven-numbered common lines among the common lines.

A first sensor pixel between the two sensor pixels may be connected to ajth (j is a natural number) common line and a (j+1)th common line, and asecond sensor pixel between the two sensor pixels may be connected tothe (j+1)th common line and a (j+2)th common line.

During a first period in one frame period, the power supply unit maysupply a first common voltage to the jth and (j+2)th common lines, andsupply a second common voltage having a level lower than that of thefirst common voltage to the (j+1)th common line. During a second periodin the one frame period, the power supply unit may supply the secondcommon voltage to the jth and (j+2)th common lines, and supply the firstcommon voltage to the (j+1)th common line.

The first period and the second period may not overlap with each other.

The first sensor pixel may provide the output signal to the read-outcircuit during the first period.

When the output signal is provided through the jth common line, theread-out circuit may determine that a touch has been generated on thefirst sensor pixel.

When the output signal is provided through the (j+1)th common line, theread-out circuit may determine that any touch has not been generated onthe first sensor pixel.

The second sensor pixel may provide the output signal to the read-outcircuit during the second period.

A sensor pixel connected to a jth common line, a (j+1)th common line, anith (i is a natural number) sensor scan line, and an (i+1)th sensor scanline among the sensor pixels may include: a sensor electrode; a firsttransistor having a gate electrode connected to the sensor electrode, afirst electrode connected to a first node, and a second electrodeconnected to a second node; a second transistor having a gate electrodeconnected to the (i+1)th sensor scan line, a first electrode connectedto the jth common line, and a second electrode connected to the firstnode; a third transistor having a gate electrode connected to the ithsensor scan line, a first electrode connected to the jth common line,and a second electrode connected to the sensor electrode; and a fourthtransistor having a first electrode connected to the second node, and agate electrode and a second electrode, which are connected to the(j+1)th common line.

The sensor pixel may further include a capacitor electrode that forms afirst capacitor together with the sensor electrode.

When the touch is generated, the sensor electrode may form a secondcapacitor together with a finger of a user.

When the sensor scan signal is supplied to the (i+1)th sensor scan line,the sensor pixel may provide the output signal to the read-out circuit.

According to another aspect of the present disclosure, there is provideda touch sensor including: a plurality of sensor pixels; a sensor scandriver configured to supply sensor scan signals to the sensor pixelsthrough sensor scan lines; a power supply unit configured to supplycommon voltages to the sensor pixels through common lines; and aread-out circuit connected to the sensor pixels through the commonlines, the read-out circuit configured to sense a touch by using anoutput signal output through the common lines, wherein a sensor pixelconnected to a jth (j is a natural number), a (j+1)th common line, anith (i is a natural number) sensor scan line, and an (i+1)th sensor scanline among the sensor pixels includes: a sensor electrode; a firsttransistor having a gate electrode connected to the sensor electrode, afirst electrode connected to a first node, and a second electrodeconnected to a second node; a second transistor having a gate electrodeconnected to the (i+1)th sensor scan line, a first electrode connectedto the jth common line, and a second electrode connected to the firstnode; a third transistor having a gate electrode connected to the ithsensor scan line, a first electrode connected to the jth common line,and a second electrode connected to the sensor electrode; and a fourthtransistor having a first electrode connected to the second node, and agate electrode and a second electrode, which are connected to the(j+1)th common line.

The sensor pixel may be activated when a first common voltage issupplied to the jth common line, and a second common voltage having alevel lower than that of the first common voltage is supplied to the(j+1)th common line. The sensor pixel may be non-activated when thesecond common voltage is supplied to the jth common line and, the firstcommon voltage is supplied to the (j+1)th common line.

When the sensor pixel is activated, and a touch of a user is generatedon the sensor pixel, the output signal may be provided to the read-outcircuit through the jth common line via the first, second, and fourthtransistors.

When the sensor pixel is activated, and the touch of the user is notgenerated on the sensor pixel, the output signal may be provided to theread-out circuit through the (j+1)th common line.

According to still another aspect of the present disclosure, there isprovided a display device including: display pixels configured todisplay an image; a plurality of sensor pixels disposed on the displaypixels; a sensor scan driver configured to supply sensor scan signals tothe sensor pixels through sensor scan lines; a power supply unitconfigured to supply common voltages to the sensor pixels through commonlines; and a read-out circuit connected to the sensor pixels through thecommon lines, the read-out circuit configured to sense a touch by usingan output signal output through the common lines, wherein two sensorpixels adjacent to each other among the sensor pixels share one commonline.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments will now be described more fully hereinafter withreference to the accompanying drawings; however, they may be embodied indifferent forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the example embodiments to those skilled in the art.

In the drawing figures, dimensions may be exaggerated for clarity ofillustration. It will be understood that when an element is referred toas being “between” two elements, it can be the only element between thetwo elements, or one or more intervening elements may also be present.Like reference numerals refer to like elements throughout.

FIG. 1 is a view illustrating a display device according to anembodiment.

FIG. 2 is a view illustrating a touch sensor according to an embodimentof the present disclosure.

FIG. 3 is a view illustrating a partial section of the touch sensorshown in FIG. 2.

FIG. 4 is a plan view of sensor pixels according to an embodiment of thepresent disclosure.

FIGS. 5A and 5B are views illustrating capacitances of capacitors,changed depending on ridges and valleys of a fingerprint.

FIG. 6 is a circuit diagram illustrating an embodiment of sensor pixelsshown in FIG. 2.

FIG. 7 is a timing diagram illustrating an operation of the sensor pixelshown in FIG. 6.

FIG. 8 is a circuit diagram illustrating operations of sensor pixelsaccording to an embodiment of the present disclosure.

FIGS. 9A and 9B are conceptual views illustrating an operation of atouch sensor according to an embodiment of the present disclosure.

FIG. 10 is a view illustrating a display pixel unit and a displaydriving unit according to an embodiment of the present disclosure.

FIG. 11 is a view illustrating an embodiment of a display pixel shown inFIG. 10.

DETAILED DESCRIPTION

The specific structural or functional description disclosed herein ismerely illustrative for the purpose of describing embodiments accordingto the concept of the present disclosure. The embodiments according tothe concept of the present disclosure can be implemented in variousforms, and cannot be construed as limited to the embodiments set forthherein.

The embodiments according to the concept of the present disclosure canbe variously modified and have various shapes. Thus, the embodiments areillustrated in the drawings and are intended to be described herein indetail. However, the embodiments according to the concept of the presentdisclosure are not construed as limited to specified disclosures, andinclude all changes, equivalents, or substitutes that do not depart fromthe spirit and technical scope of the present disclosure.

While terms such as “first” and “second” may be used to describe variouscomponents, such components must not be understood as being limited tothe above terms. The above terms are used only to distinguish onecomponent from another. For example, a first component may be referredto as a second component without departing from the scope of rights ofthe present disclosure, and likewise a second component may be referredto as a first component.

It will be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements mayalso be present. In contrast, when an element is referred to as being“directly connected” or “directly coupled” to another element, nointervening elements are present. Meanwhile, other expressionsdescribing relationships between components such as “˜between,”“immediately˜between” or “adjacent to˜” and “directly adjacent to˜” maybe construed similarly.

The terms used in the present application are merely used to describeparticular embodiments, and are not intended to limit the presentdisclosure. Singular forms in the present disclosure are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that terms such as “including”or “having,” etc., are intended to indicate the existence of thefeatures, numbers, operations, actions, components, parts, orcombinations thereof disclosed in the specification, and are notintended to preclude the possibility that one or more other features,numbers, operations, actions, components, parts, or combinations thereofmay exist or may be added.

So far as not being differently defined, all terms used herein includingtechnical or scientific terminologies have meanings that they arecommonly understood by those skilled in the art to which the presentdisclosure pertains. The terms having the definitions as defined in thedictionary should be understood such that they have meanings consistentwith the context of the related technique. So far as not being clearlydefined in this application, terms should not be understood in anideally or excessively formal way.

FIG. 1 is a view illustrating a display device according to anembodiment.

Referring to FIG. 1, the display device 10 according to the embodimentof the present disclosure may include a display panel 12 that display animage and a touch sensing layer 11 disposed on one surface of thedisplay panel 12.

The display device 10 may be provided in a rectangular plate shapehaving two pairs of sides parallel to each other. When the displaydevice 10 is provided in the rectangular plate shape, any one pair ofsides among the two pairs of sides may be provided longer than the otherpair of sides. However, the present disclosure is not limited thereto,and the display device 10 may be provided in various shapes such as acircular shape and a rectangular shape including curved corners.

The display panel 12 may display, on one surface thereof, visualinformation, e.g., text, a video, a picture, a two-dimensional orthree-dimensional image, etc., and the visual information may bedisplayed as an “image.” The kind of the display panel 12 is notparticularly limited to ones that display images.

The touch sensing layer 11 may include a touch sensor that recognizes atouch event generated by a finger 300 of a user or a separated inputmeans. The touch sensor is used to sense a touch and/or a pressure byusing sensing electrodes, and the kind of the touch sensor is notparticularly limited. For example, the touch sensor may be implementedusing a capacitive method, a piezoresistive method, or the like.

FIG. 2 is a view illustrating a touch sensor according to an embodimentof the present disclosure. FIG. 3 is a view illustrating a partialsection of the touch sensor shown in FIG. 2.

Referring to FIGS. 2 and 3, the touch sensor 100 according to theembodiment of the present disclosure may recognize a touch input by auser.

For example, a recognizing operation implementable by the touch sensor100 may include at least one of identification of a position at which atouch is generated, recognition of a fingerprint of a touched finger,and sensing of a touch pressure.

The touch sensor 100 may include a substrate SUB, sensor pixels SP, asensor scan driver 110, a read-out circuit 120, and a power supply unit130.

The substrate SUB may be made of an insulative material such as glass orresin. Also, the substrate SUB may be made of a material havingflexibility to be bendable or foldable. The substrate SUB may have asingle- or multi-layered structure.

For example, the substrate SUB may include at least one of polystyrene,polyvinyl alcohol, polymethyl methacrylate, polyethersulfone,polyacrylate, polyetherimide, polyethylene naphthalate, polyethyleneterephthalate, polyphenylene sulfide, polyarylate, polyimide,polycarbonate, triacetate cellulose, and cellulose acetate propionate.

However, the material constituting the substrate SUB may be variouslychanged, and the substrate SUB may be made of fiber glass reinforcedplastic (FRP), or the like.

The sensor pixels SP may be located on the substrate SUB. Also, thesensor pixels SP may be connected to sensor scan lines SSL1 to SSLn andcommon lines CL1 to CLm.

The sensor pixels SP may receive sensor scan signals input through thesensor scan lines SSL1 to SSLn. The sensor pixels SP may output apredetermined output current corresponding to a touch state to some ofthe common lines CL1 to CLm during a supply period of the sensor scansignal.

In particular, two sensor pixel columns adjacent to each other among thesensor pixels SP may share one common line (any one of CL1 to CLm). Inthis case, the two sensor pixel columns are not simultaneouslyactivated, and only one sensor pixel column corresponding to the supplyof a common voltage may be activated for touch sensing.

For example, one sensor pixel column between the two sensor pixelcolumns may provide an output current to the read-out circuit 120 duringonly a first period in one frame period, and the other sensor pixelcolumn may provide the output current to the read-out circuit 120 duringonly a second period different from the first period in the one frameperiod.

The sensor scan lines SSL1 to SSLn may be provided on the substrate SUB.The sensor scan lines SSL1 to SSLn may extend in a first direction(e.g., an x-axis direction) to be connected to the sensor pixels SP inunits of sensor pixel rows.

In particular, at least two sensor pixel rows among the sensor pixelrows may be connected to the same sensor scan line (one of SSL1 toSSLn), and simultaneously receive a sensor scan signal input from thesensor scan line (the one of SSL1 to SSLn).

The common lines CL1 to CLm may be located on the substrate SUB. Thecommon lines CL1 to CLm may extend in a second direction (e.g., a y-axisdirection) to be connected to the sensor pixels SP in units of lines.

In particular, at least two sensor pixel columns among sensor pixelcolumns may be connected to the same common line (one of CL1 to CLm),and simultaneously receive a common voltage supplied from the commonline (the one of CL1 to CLm). That is, adjacent sensor pixel columns mayshare one common line (one of CL1 to CLm).

In addition, the sensor pixels SP may provide an output current to theread-out circuit 120 through some of the common lines CL1 to CLm,corresponding to a touch of the user.

Meanwhile, the arrangement direction of the common lines CL1 to CLm maybe variously changed. For example, the common lines CL1 to CLm may bedisposed in parallel to the sensor scan lines SSL1 to SSLn.

The sensor scan driver 110 may supply sensor scan signals to the sensorpixels SP through the sensor scan lines SSL1 to SSLn.

In some embodiments, the sensor scan driver 110 may sequentially outputsensor scan signals to the sensor scan lines SSL1 to SSLn.

The sensor scan signal may have a voltage level at which a transistorsupplied with the sensor scan signal can be turned on.

The sensor scan driver 110 may be directly mounted on the substrate SUB,or be connected to the substrate SUB through a separate component suchas a flexible printed circuit board.

The read-out circuit 120 may receive an output current from the sensorpixels SP through the common lines CL1 to CLm.

For example, when the sensor scan driver 110 sequentially supplies asensor scan signal, the sensor pixels SP may be selected in units oflines, and the read-out circuit 120 may sequentially receive an outputcurrent received from the selected sensor pixels SP through the commonlines CL1 to CLm.

In this case, if an output current is supplied from a first common linebetween two common lines connected to one sensor pixel SP, the read-outcircuit 120 may determine that a touch has been generated on thecorresponding sensor pixel SP.

On the other hand, if the output current is supplied from a secondcommon line between the two common lines connected to the one sensorpixel SP, the read-out circuit 120 may determine that no touch has beengenerated on the corresponding sensor pixel SP.

Here, the first common line refers to a line to which a common voltagehaving a first voltage level (hereinafter, referred to as a first commonvoltage) is supplied, and the second common line refers to a line towhich a common voltage having a second voltage level lower than thefirst voltage level (hereinafter, referred to as a second commonvoltage) is supplied.

By using the determined result, the read-out circuit 120 may generateinformation on the position of a touch occurring on the sensor pixelsSP, a pressure applied by the touch, valleys and ridges included in afingerprint of a finger, and the like.

The read-out circuit 120 may be directly mounted on the substrate SUB,or be connected to the substrate SUB through a separate component suchas a flexible printed circuit board.

The power supply unit 130 may supply common voltages to the sensorpixels SP through the common lines CL1 to CLm. In this case, the powersupply unit 130 may supply the first common voltage to some common linesamong the common lines CL1 to CLm, and supply the second common voltageto the other common lines.

For example, the power supply unit 130 may supply the first commonvoltage or the second common voltage to odd-numbered common lines CL1,CL3, . . . , and supply the second common voltage or the first commonvoltage to even-numbered common lines CL2, CL4, . . . . That is, thepower supply unit 130 may simultaneously supply common voltages havingdifferent voltage levels to the odd-numbered common lines CL1, CL3, . .. and the even-numbered common lines CL2, CL4, . . . .

In addition, the power supply unit 130 may alternately supply the firstcommon voltage and the second common voltage to each of the common linesCL1 to CLm for every certain period.

For example, during a first period in one frame period, the power supplyunit 130 may supply the first common voltage the odd-numbered commonlines CL1, CL3, . . . , and supply the second common voltage to theeven-numbered common lines CL2, CL4, . . . . After that, during a secondperiod not overlapping with the first period in the one frame period,the power supply unit 130 may supply the second common voltage theodd-numbered common lines CL1, CL3, . . . , and supply the first commonvoltage to the even-numbered common lines CL2, CL4, . . . .

In FIG. 2, it is illustrated that the sensor scan driver 110, theread-out circuit 120, and the power supply unit 130 are individuallyprovided, but at least some of the components may be integrated, ifnecessary.

In addition, the sensor scan driver 110, the read-out circuit 120, andthe power supply unit 130 may be installed in various ways such as chipon glass, chip on plastic, tape carrier package, and chip on film.

FIG. 4 is a plan view of sensor pixels according to an embodiment of thepresent disclosure.

For convenience of description, a first sensor pixel SP1 connected toith and (i+1)th sensor scan lines SSLi and SSLi+1 and jth and (j+1)thcommon lines CLj and CLj+1 and a second sensor pixel SP2 connected theith and (i+1)th sensor scan lines SSLi and SSLi+1 and the (j+1)th commonline CLj+1 and a (j+2)th common line CLj+2 are illustrated in FIG. 4(here, i and j are natural numbers).

Referring to FIG. 4, each of the first and second sensor pixels SP1 andSP2 according to the embodiment of the present disclosure may include asensor electrode 240, a first transistor T1, a second transistor T2, athird transistor T3, a fourth transistor T4, and a capacitor electrode250.

Hereinafter, only connection relationships between components includedin the first sensor pixel SP1 will be described in detail to avoidredundancy.

The first transistor T1 may control an output current flowing in the jthcommon line CLj. To this end, the first transistor T1 may be connectedbetween the second transistor T2 and the fourth transistor T4.

For example, the first transistor T1 may include a first electrodeconnected to a second electrode 223 of the second transistor T2, asecond electrode 213 connected to a first electrode 242 of the fourthtransistor T4, a gate electrode 214 connected to the sensor electrode240, and a semiconductor layer 211 connected between the first electrode212 and the second electrode 213.

In addition, the gate electrode 214, the first electrode 212, and thesecond electrode 213 of the first transistor T1 may be connected toother components through contact holes CH1, CH2, and CH3, respectively.

Therefore, the first transistor T1 may control an output current outputto the jth common line CLj, corresponding to the potential of the sensorelectrode 240.

The second transistor T2 may be connected between the jth common lineCLj and the first transistor T2.

For example, the second transistor T2 may include a first electrode 222connected to the jth common line CLj, the second electrode 223 connectedto the first electrode 212 of the first transistor T1, a gate electrode224 connected to the (i+1)th sensor scan line SSLi+1, and asemiconductor layer 221 connected between the first electrode 222 andthe second electrode 223.

In addition, the first electrode 222 and the second electrode 223 of thesecond transistor T2 may be connected to other components throughcontact holes CH4 and CH5, respectively.

Therefore, the second transistor T2 may be turned on when a sensor scansignal is supplied to the (i+1)th sensor scan line SSLi+1. When thesecond transistor T2 is turned on, the first common voltage or thesecond common voltage may be applied to the first electrode 212 of thefirst transistor T1.

The third transistor T3 may be connected between the jth common line CLjand the sensor electrode 240.

For example, the third transistor T3 may include a first electrode 232connected to the jth common line CLj, a second electrode 233 connectedto the sensor electrode 240, a gate electrode 234 connected to the ithsensor scan line SSLi, and a semiconductor layer 231 connected betweenthe first electrode 232 and the second electrode 233.

In addition, the first electrode 232 and the second electrode 233 of thethird transistor T3 may be connected to other components through contactholes CH6 and CH7, respectively.

Therefore, the third transistor T3 may be turned on when a sensor scansignal is supplied to the ith sensor scan line SSLi. When the thirdtransistor T3 is turned on, the voltage of the sensor electrode 240 maybe initialized to the first common voltage or the second common voltage.

The fourth transistor T4 may be connected between the first transistorT1 and the (j+1)th common line CLj+1.

For example, the fourth transistor T4 may include the first electrode242 connected to the second electrode 213 of the first transistor T1, asecond electrode 243 and a gate electrode 244, which are connected tothe (j+1)th common line CLj+1, and a semiconductor layer 241 connectedbetween the first electrode 242 and the second electrode 243.

In addition, the first electrode 242, the second electrode 243, and thegate electrode 244 of the fourth transistor T4 may be connected to othercomponents through contact holes CH8, CH9, and CH10, respectively.

Therefore, the fourth transistor T4 may be turned on when the firstcommon voltage is supplied to the first electrode 242 and the secondcommon voltage is supplied to the (j+1)th common line CLj+1. That is,the fourth transistor T4 may be turned on when the first common voltagesupplied to the jth common line CLj is supplied to the first electrode242 via the first transistor T1 and the second common voltage issupplied to the (j+1)th common line CLj+1.

On the other hand, the fourth transistor T4 may be turned off when thesecond common voltage is supplied to the first electrode 242 and thefirst common voltage is supplied to the (j+1)th common line CLj+1. Thatis, the fourth transistor T4 may be turned off when the second commonvoltage supplied to the jth common line CLj is supplied to the firstelectrode 242 via the first transistor T1 and the first common voltageis supplied to the (j+1)th common line CLj+1.

When the fourth transistor T4 is turned on, the first transistor T1 mayprovide an output current to the jth common line CLj, corresponding tothe potential of the sensor electrode 240.

The capacitor electrode 250 may be located to overlap with the sensorelectrode 240. Accordingly, the capacitor electrode 250 can form a firstcapacitor together with the sensor electrode 240.

In addition, the capacitor electrode 250 may be connected to the ithsensor scan line SSLi. For example, the capacitor electrode 250 may beconnected to the ith sensor scan line SSLi through the gate electrode224 of the second transistor T2.

In this case, the capacitor electrode 250 and the gate electrode 224 ofthe second transistor T2 may be formed of the same material as the ithsensor scan line SSLi.

The sensor electrode 240 may form a capacitor together with thecapacitor electrode 250. In addition, the sensor electrode 240 may forma capacitor, corresponding to a touch of a finger or the like.

In addition, the sensor electrode 240 may include a conductive material.

For example, the conductive material may include at least one of metals,any alloy thereof, a conductive polymer, and a transparent conductivematerial.

For example, the metal may include at least one of copper, silver, gold,platinum, palladium, nickel, tin, aluminum, cobalt, rhodium, iridium,iron, ruthenium, osmium, manganese, molybdenum, tungsten, niobium,tantalum, titanium, bismuth, antimony, and lead.

For example, the conductive polymer may include at least one ofpolythiophene-based, polypyrrole-based, polyaniline-based,polyacetylene-based, and polyphenylene-based compounds, and mixturesthereof. In particular, a polythiophene-based compound made of aPEDOT/PSS compound may be used as the conductive polymer.

For example, the transparent conductive material may include at leastone of silver nanowire (AgNW), indium tin oxide (ITO), indium zinc oxide(IZO), antimony zinc oxide (AZO), indium tin zinc oxide (ITZO), zincoxide (ZnO), tin oxide (SnO₂), carbon nano tube (CNT), and graphene.

Meanwhile, the first sensor pixel SP1 and the second sensor pixel SP2may share the (j+1)th common line CLj+1. That is, the fourth transistorT4 of the first sensor pixel SP1 and the second and third transistors T2and T3 of the second sensor pixel SP2 may be connected to the (j+1)thcommon line CLj+1. Therefore, when the first common voltage or thesecond common voltage is supplied to the (j+1)th common line CLj+1, thefirst sensor pixel SP1 and the second sensor pixel SP2 may besimultaneously supplied with the first common voltage or the secondcommon voltage.

FIGS. 5A and 5B are views illustrating capacitances of capacitors,changed depending on ridges and valleys of a fingerprint. In particular,a case where a ridge 310 of a fingerprint of a finger 300 is located ona sensor pixel SP is illustrated in FIG. 5A, and a case where a valley320 of the finger print of the finger 300 is located on the sensor pixelSP is illustrated in FIG. 5B.

Referring to FIGS. 5A and 5B, a sensor electrode 240 and a capacitorelectrode 250 may form a first capacitor C1. The sensor electrode 240and the capacitor electrode 250 may be located to be spaced apart fromeach other, and a least one insulating layer (not shown) may be locatedbetween the sensor electrode 240 and the capacitor electrode 250.

In addition, when the finger 300 of the user is located on the sensorpixel SP so as to recognize the fingerprint, the sensor electrode 240and the finger 300 may form a second capacitor C2.

In this case, the second capacitor C2 is a variable capacitor, and thecapacitance of the second capacitor C2 may be changed depending onwhether the ridge 310 or the valley 320 of the fingerprint is located onthe sensor electrode 240.

That is, since a distance between the ridge 310 and the sensor electrode240 is shorter than that between the valley 320 and the sensor electrode240, a capacitance of the second capacitor C2 when the ridge 310 islocated on the sensor electrode 240 as shown in FIG. 5A may be differentfrom that of the second capacitor C2 when the valley 320 is located onthe sensor electrode 240 as shown in FIG. 5B.

A change in capacitance of the second capacitor C2 has influence on anoutput current of the sensor pixel SP, and thus the read-out circuit 120can recognize the fingerprint of the user by sensing a variation of theoutput current.

FIG. 6 is a circuit diagram illustrating an embodiment of the sensorpixels shown in FIG. 2. FIG. 7 is a timing diagram illustrating anoperation of the sensor pixel shown in FIG. 6.

For convenience of description, a first sensor pixel SP1 connected toith and (i+1)th sensor scan lines SSLi and SSLi+1 and jth and (j+1)thcommon lines CLj and CLj+1 and a second sensor pixel SP2 connected theith and (i+1)th sensor scan lines SSLi and SSLi+1 and the (j+1)th commonline CLj+1 and a (j+2)th common line CLj+2 are illustrated in FIG. 6.

In addition, a first sensor scan signal SS1 supplied to a first sensorscan lines SSL1 to an nth sensor scan signal SSn supplied to an nthsensor scan line SSLn are illustrated in FIG. 7, and a common voltageCLodd to the odd-numbered common lines CL1, CL3, . . . and a commonvoltage CLeven supplied to the even-numbered common lines CL2, CL4, . .. are illustrated in FIG. 7.

Each of the first and second sensor pixels SP1 and SP2 may include afirst capacitor C1, a first transistor T1, a second transistor T2, athird transistor T3, and a fourth transistor T4.

Hereinafter, only connection relationships between components includedin the first sensor pixel SP1 will be described in detail to avoidredundancy.

As described above, the first capacitor C1 may be formed a sensorelectrode 240 connected to the third node N3 and a capacitor electrode250 connected to the (i+1)th sensor scan line SSLi+1.

In addition, a second capacitor C2 is a variable capacitor, and may beformed by the sensor electrode 240 and the finger 300 of the user asdescribed above. In this case, the capacitance of the second capacitorC2 may be changed depending on a distance between the sensor electrode240 and the finger 300, whether a ridge or valley of the fingerprint islocated on the sensor electrode 240, the intensity of a pressuregenerated by a touch, or the like.

The first transistor T1 may include a first electrode connected to afirst node N1, a second electrode connected to a second node N2, and agate electrode connected to the third node N3.

The second transistor T2 may include a first electrode connected to thejth common line CLj, a second electrode connected to the first node N1,and a gate electrode connected to the (i+1)th sensor scan line SSLi+1.

The third transistor T3 may include a first electrode connected to thejth common line CLj, a second electrode connected to the third node N3,and a gate electrode connected to the ith sensor scan line SSLi.

The fourth transistor T4 may include a first electrode connected to thesecond node N2, and a second electrode and a gate electrode, which areconnected to the (j+1)th common line CLj+1.

Here, the first node N1 is a node to which the first electrode of thefirst transistor T1 and the second electrode of the second transistor T2are commonly connected, the second node N2 is a node to which the secondelectrode of the first transistor T1 and the first electrode of thefourth transistor T4 are commonly connected, and the third node N3 is anode to which the sensor electrode 240, the gate electrode of the firsttransistor T1, and the second electrode of the third transistor T3 arecommonly connected.

Here, the first electrode of each of the transistors T1, T2, T3, and T4may be set as any one of source and drain electrodes, and the secondelectrode of each of the transistors T1, T2, T3, and T4 may be set as anelectrode different from the first electrode. For example, if the firstelectrode is set as a source electrode, the second electrode may be setas a drain electrode.

In FIG. 6, a case where the transistors T1, T2, T3, and T4 are PMOStransistors is illustrated as an example. However, in anotherembodiment, the transistors T1, T2, T3, and T4 may be implemented asNMOS transistors.

Referring to FIG. 7, there are illustrated first to nth sensor scansignals SS1 to SSn supplied during a first period PD1 and a secondperiod PD2 in one frame period 1 FRAME, a common voltage CLodd suppliedto the odd-numbered common lines CL1, CL3, . . . , and a common voltageCLeven supplied to the even-numbered common lines CL2, CL4, . . . .

Here, the one frame period 1 FRAME may mean a period in which the sensorscan signals SS1 to SSn are supplied to all sensor pixels at leasttwice, or mean a period corresponding to one period of a verticalsynchronization signal supplied to the display panel 12.

The first to nth sensor signals SS1 to SSn may be sequentially suppliedto first to nth sensor scan lines SSL1 to SSLn during the first periodPD1, and be repeatedly supplied to the first to nth sensor scan linesSSL1 to SSLn during the second period PD2 not overlapping with the firstperiod PD1.

In addition, the common voltage CLodd having a first voltage level V1may be supplied to the odd-numbered common lines CL1, CL3, . . . duringthe first period PD1, and the common voltage CLodd having a secondvoltage level V2 may be supplied to the odd-numbered common lines CL1,CL3, . . . during the second period PD2.

In addition, the common voltage CLeven having the second voltage levelV2 may be supplied to the even-numbered common lines CL2, CL4, . . .during the first period PD1, and the common voltage CLeven having thefirst voltage level V1 may be supplied to the even-numbered common linesCL2, CL4, . . . during the second period PD2.

Accordingly, during the first period PD1, the common voltage CLoddhaving the first voltage level V1 may be supplied to the first electrodeof the second transistor T2 and the first electrode of the thirdtransistor T3 on an odd-numbered sensor pixel column, and the commonvoltage CLeven having the second voltage level V2 may be supplied to thesecond electrode of the fourth transistor T4 on the odd-numbered sensorpixel column.

Hereinafter, operations of the first sensor pixel SP1 and the secondsensor pixel SP2 will be described by assuming that the first sensorpixel SP1 is located on an odd-numbered sensor pixel column and thesecond sensor pixel SP2 is located on an even-numbered sensor pixelcolumn.

If an ith sensor scan signal SSi is supplied during the first periodPD1, the third transistor T3 of the first sensor pixel SP1 may be turnedon such that the third node N3 is initialized to the first voltage levelV1. In addition, the third transistor T3 of the second sensor pixel SP2may be turned on such that the third node N3 is initialized to thesecond voltage level V2.

After that, if an (i+1)th sensor scan signal SSi+1 is supplied duringthe first period PD1, the second transistor T2 of the first sensor pixelSP1 may be turned on such that the common voltage CLodd having the firstvoltage level V1 is supplied to the first node N1. In addition, thesecond transistor T2 of the second sensor pixel SP2 may be turned onsuch that the common voltage CLeven having the second voltage level V2is supplied to the first node N1.

In this case, the first transistor T1 may control the supply of anoutput current output corresponding to a gate voltage (a voltage appliedto the third node N3), and the gate voltage of the first transistor T1may be determined according to the following equation.

Vg={CA2/(CA1+CA2)}*Vs

Here, Vg is a gate voltage, CA1 is a capacitance of the first capacitorC1, CA2 is a capacitance of the second capacitor C2, and Vs is a voltagevariation of the (i+1)th scan signal SSi+1 supplied to the (i+1)thsensor scan line SSLi+1.

When a touch is generated by the user, the first transistor T1 may beturned on according to the equation. On the other hand, when any touchis not generated by the user, the first transistor T1 may be turned offaccording to the equation.

When the first transistor T1 of the first sensor pixel SP1 is turned onduring the first period PD1, the common voltage CLodd having the firstvoltage level V1 may be supplied to the first electrode of the fourthtransistor T4. In addition, when the first transistor T1 of the secondsensor pixel SP2 is turned on, the common voltage CLeven having thesecond voltage level V2 may be supplied to the first electrode of thefourth transistor T4.

At this time, since the common voltage CLodd having the first voltagelevel V1 is supplied to the first electrode of the fourth transistor T4of the first sensor pixel SP1 and the common voltage CLeven having thesecond voltage level V2 is supplied to the second electrode and the gateelectrode of the fourth transistor T4, the fourth transistor T4 may beturned on. In this case, an output current may be provided to the jthcommon line CLj via the fourth, first, and second transistors T4, T1,and T2.

On the other hand, since the common voltage CLeven having the secondvoltage level V2 is supplied to the first electrode of the fourthtransistor T4 of the second sensor pixel SP2 and the common voltageCLodd having the first voltage level V1 is supplied to the secondelectrode and the gate electrode of the fourth transistor T4, the fourthtransistor T4 may be turned off. In this case, the second sensor pixelSP2 cannot provide any output current to the read-out circuit 120.

As described above, the odd-numbered sensor pixel column may beactivated for touch sensing during the first period PD1, but theeven-numbered sensor pixel column may be non-activated.

After that, during the second period PD2, the common voltage CLoddhaving the second voltage level V2 may be supplied to the firstelectrode of the second transistor T2 and the first electrode of thethird transistor T3 on the odd-numbered sensor pixel column, and thecommon voltage CLeven having the first voltage level V1 may be suppliedto the second electrode of the fourth transistor T4.

In addition, during the second period PD2, the common voltage CLevenhaving the first voltage level V1 may be supplied to the first electrodeof the second transistor T2 and the first electrode of the thirdtransistor T3 on the even-numbered sensor pixel column, and the commonvoltage CLodd having the second voltage level V2 may be supplied to thesecond electrode of the fourth transistor T4.

The first sensor pixel SP1 may perform the same operation as the secondsensor pixel SP2 during the first period, and the second sensor pixelSP2 may perform the same operation as the first sensor pixel SP1 duringthe first period. Hereinafter, overlapping descriptions will be omitted.

Consequently, during the second period PD2, the odd-numbered sensorpixel columns are non-activated, and the even-numbered sensor pixelcolumns are activated for touch sensing.

As described above, in the touch sensor 100 according to the embodimentof the present disclosure, the odd-numbered sensor pixel columns can beactivated during the first period PD1 in the one frame period 1 FRAME,and the even-numbered sensor pixel columns can be activated during thesecond period PD2.

Meanwhile, although a case where the first period PD1 in the one frameperiod 1 FRAME precedes the second period PD2 is illustrated in FIG. 7,the present disclosure is not limited thereto, and the second period PD2may precede the first period PD1. That is, during the one frame period 1FRAME, the even-numbered sensor pixel columns may be first activated,and the odd-numbered sensor pixel columns may be then activated.

In addition, although a case where one first period PD1 and one secondperiod PD2 exist in the one frame period 1 FRAME is illustrated in FIG.7, the present disclosure is not limited thereto, and a plurality offirst periods PD1 and a plurality of second periods PD2 may exist in theone frame period 1 FRAME.

FIG. 8 is a circuit diagram illustrating operations of sensor pixelsaccording to an embodiment of the present disclosure.

Referring to FIG. 8, there are illustrated first to fourth sensor pixelsSP1 to SP4 commonly connected to first and second sensor scan lines SSL1and SSL2. The first sensor pixel SP1 is connected to the first andsecond common lines CL1 and CL2, the second sensor pixel SP2 isconnected to the second and third common lines CL2 and CL3, the thirdsensor pixel SP3 is connected to the third and fourth common lines CL3and CL4, and the fourth sensor pixel SP4 is connected to the fourth andfifth common lines CL4 and CL5.

In addition, a common voltage having the first voltage level V1 may besupplied to the first, third, and fifth common lines CL1, CL3, and CL5,and a common voltage having the second voltage level V2 may be suppliedto the second and fourth common lines CL2 and CL4.

Accordingly, the first and third sensor pixels SP1 and SP3 are activatedfor touch sensing, but the second and fourth sensor pixels SP2 and SP4may be non-activated.

In FIG. 8, arrows are illustrated to describe a route of an outputcurrent changed depending on whether a touch is generated by the user.Hereinafter, a case where any touch is not generated on the first sensorpixel SP1 and a case where a touch is generated on the third sensorpixel SP3 are described to be distinguished from each other. However,this is merely an embodiment for convenience of description, and theembodiment of the present disclosure is not limited thereto.

Meanwhile, when an output current is supplied from a common lineconnected to the second and third transistors T2 and T3 of an activatedsensor pixel, the read-out circuit 120 may determine that a touch hasbeen generated on the corresponding sensor pixel. In addition, when anoutput current is supplied from a common line connected to the fourthtransistor T4 of an activated sensor pixel, the read-out circuit 120 maydetermine that any touch has not been generated on the correspondingsensor pixel. That is, the read-out circuit 120 may determine thegeneration of a touch, based on whether the output current is suppliedfrom the common line connected to the fourth transistor T4 of theactivated sensor pixel.

First, although the second sensor scan signal SS2 is supplied to thegate electrode of the second transistor T2 of the first sensor pixelSP1, any touch has not been generated on the first sensor pixel SP1, andhence the first transistor T1 is turned off. Therefore, the outputcurrent of the first sensor pixel SP1 is provided to the read-outcircuit 120 through the second common line CL2 without passing throughthe first transistor T1.

In addition, if the second sensor scan signal SS2 is supplied to thegate electrode of the second transistor T2 of the third sensor pixelSP3, a touch has been generated on the third sensor pixel SP3, and hencethe first transistor T1 is turned on. Therefore, the output current ofthe third sensor pixel SP3 is provided to the third common line CL3 viathe fourth, first, and second transistors T4, T1, and T2.

Consequently, the read-out circuit 120 may determine that any touch hasnot been generated on the first sensor pixel SP1 between the activatedfirst and third sensor pixels SP1 and SP3, and a touch has beengenerated on the third sensor pixel SP3.

FIGS. 9A and 9B are conceptual views illustrating an operation of atouch sensor according to an embodiment of the present disclosure.

In FIGS. 9A and 9B, there are first to ninth sensor scan lines SSL1 toSSL9, first to ninth common lines CL1 to CL9, and sensor pixels SPhaving an 8×8 matrix structure. For convenience of description, thisconceptually illustrates the touch sensor 100 shown in FIG. 2. Thenumbers, arrangements, etc. of the first to ninth sensor scan lines SSL1to SSL9, the first to ninth common lines CL1 to CL9, and the sensorpixels SP having the 8×8 matrix structure are not limited thereto, andmay be variously modified and implemented.

Meanwhile, some sensor pixels SP are displayed with black. However, theblack is merely displayed to describe only activated sensor pixels, anddoes not connote any specific technical meaning.

Referring to FIG. 9A, the sensor scan driver 110 may be connected to thesensor pixels SP through the first to ninth scan lines SSL1 to SSL9, andthe read-out circuit 120 and the power supply unit 130 may be connectedto the sensor pixels SP through the first to ninth common lines CL1 toCL9.

In addition, sensor pixel columns adjacent to each other may share onecommon line. For example, a first sensor pixel column and a secondsensor pixel column may be commonly connected to the second common lineCL2.

As shown in FIG. 9A, if the common voltage having the first voltagelevel V1 is supplied to the odd-numbered common lines CL1, CL3, . . . ,CL9 and the common voltage having the second voltage level V2 issupplied to the even-numbered common lines CL2, CL4, . . . , CL8, theodd-numbered sensor pixels may be activated for touch sensing, and theeven-numbered sensor pixels may be non-activated.

Referring to FIG. 9B, if the common voltage having the second voltagelevel V2 is supplied to the odd-numbered common lines CL1, CL3, . . . ,CL9 and the common voltage having the first voltage level V1 is suppliedto the even-numbered common lines CL2, CL4, . . . , CL8, theodd-numbered sensor pixels may be non-activated, and the even-numberedsensor pixels may be activated for touch sensing.

As described above, the touch sensor 100 according to the embodiment ofthe present disclosure can control the sensor pixel SP to be activatedby selectively supplying the common voltage having the first voltagelevel V1 or the second voltage level V2 to the common lines.

FIG. 10 is a view illustrating a display pixel unit and a displaydriving unit according to an embodiment of the present disclosure.

Referring to FIG. 10, the display panel 12 according to the embodimentof the present disclosure may include a display pixel unit 500 and adisplay driving unit 400.

The display pixel unit 500 may include a plurality of display pixels DP.

The display pixels DP may be connected to data lines D1 to Dq anddisplay scan lines DS1 to DSp. For example, the display pixels DP may bearranged in a matrix form at intersection portions of the data lines D1to Dq and the display scan lines DS1 to DSp.

In addition, each of the display pixels DP may be supplied with a datasignal and a display scan signal through the data lines D1 to Dq and thedisplay scan lines DS1 to DSp.

Each of the display pixels DP may include a light emitting device (e.g.,an organic light emitting diode), and light corresponding to a datasignal may be emitted from the display pixel DP by current flowing froma first power source ELVDD to a second power source ELVSS via the lightemitting device.

The display driving unit 400 may include a scan driver 410, a datadriver 420, and a timing controller 450.

The scan driver 410 may supply scan signals to the display scan linesDS1 to DSp in response to a scan driver control signal SCS. For example,the scan driver 410 may sequentially supply display scan signals to thedisplay scan lines DS1 to DSp.

In order for the scan driver 410 to be connected to the display scanlines DS1 to DSp, the scan driver 410 may be directly mounted on asubstrate or be connected to the substrate through a separate componentsuch as a flexible printed circuit board.

The data driver 420 may receive a data driver control signal DCS andimage data DATA, input from the timing controller 450, to generate adata signal.

The data driver 420 may supply the generated data signal to the datalines D1 to Dq.

In order for the data driver 420 to be connected to the data lines D1 toDq, the data driver 420 may be directly mounted on the substrate or beconnected to the substrate through a separate component such as aflexible printed circuit board.

If a display scan signal is supplied to a specific display scan line,some display pixels DP connected to the specific display scan line maybe supplied with a data signal transmitted from the data lines D1 to Dq.The some display pixels DP may emit light with a luminance correspondingto the supplied data signal.

The timing controller 450 may generate control signals for controllingthe scan driver 410 and the data driver 420.

For example, the control signals may include the scan driver control SCSfor controlling the scan driver 410 and the data driver control signalDCS for controlling the data driver 420.

In addition, the timing controller 450 may supply the scan drivercontrol signal SCS to the scan driver 410, and supply the data drivercontrol signal DCS to the data driver 420.

The timing controller 450 may convert image data DATA suitable forspecifications of the data driver 420, and supply the converted imagedata to the data driver 420.

In FIG. 10, it is illustrated that the scan driver 410, the data driver420, and the timing controller 450 are individually provided, but atleast some of the components may be integrated, if necessary.

In addition, the scan driver 410, the data driver 420, and the timingcontroller 450 may be installed in various ways such as chip on glass,chip on plastic, tape carrier package, and chip on film.

FIG. 11 is a view illustrating an embodiment of the display pixel shownin FIG. 10.

For convenience of illustration, a display pixel DP connected to a pthdisplay scan line DSp and a qth data line Dq is illustrated in FIG. 11.

Referring to FIG. 11, the display pixel DP may include an organic lightemitting diode OLED and a pixel circuit PC connected to the qth dataline Dq, the pth display scan line DSp to control the organic lightemitting diode OLED.

An anode electrode of the organic light emitting diode OLED may beconnected to the pixel circuit PC, and a cathode electrode of theorganic light emitting diode OLED may be connected to the second powersource ELVSS.

The organic light emitting diode OLED may generate light with apredetermined luminance corresponding to a current supplied from thepixel circuit PC.

The pixel circuit PC may store a data signal supplied to the qth dataline Dq when a display scan signal is supplied to the pth display scanline. The pixel circuit PC may control the amount of current supplied tothe organic light emitting diode OLED, corresponding to the stored datasignal.

For example, the pixel circuit PC may include a first transistor M1, asecond transistor M2, and a storage capacitor Cst.

The first transistor M1 may be connected between the qth data line Dqand the second transistor M2.

For example, a gate electrode of the first transistor M1 may beconnected to the pth display scan line DSp, a first electrode of thefirst transistor M1 may be connected to the qth data line Dq, and asecond electrode of the first transistor M1 may be connected to a gateelectrode of the second transistor M2.

The first transistor M1 may be turned on when the display scan signal issupplied to the pth display scan line DSp, to supply a data signal fromthe qth data line Dq to the storage capacitor Cst.

In this case, the storage capacitor Cst may charge a voltagecorresponding to the data signal.

The second transistor M2 may be connected between the first power sourceELVDD and the organic light emitting diode OLED.

For example, the gate electrode of the second transistor M2 may beconnected to a first electrode of the storage capacitor Cst and thesecond electrode of the first transistor M1, a first electrode of thesecond transistor M2 may be connected to a second electrode of thestorage capacitor Cst and the first power source ELVDD, and a secondelectrode of the second transistor M2 may be connected to the anodeelectrode of the organic light emitting diode OLED.

The second transistor M2 is a driving transistor, and may control theamount of current flowing from the first power source ELVDD to thesecond power source ELVDD via the organic light emitting diode OLED,corresponding to the voltage stored in the storage capacitor Cst.

In this case, the organic light emitting diode OLED may generate lightcorresponding to the amount of current supplied from the secondtransistor M2.

Here, the first electrode of each of the transistors M1 and M2 may beset as any one of source and drain electrodes, and the second electrodeof each of the transistors M1 and M2 may be set as an electrodedifferent from the first electrode. For example, if the first electrodeis set as a source electrode, the second electrode may be set as a drainelectrode.

In FIG. 11, a case where the transistors M1 and M2 are PMOS transistorsis illustrated as an example. However, in another embodiment, thetransistors M1 and M2 may be implemented as NMOS transistors.

In the touch sensor and the display device including the same accordingto the present disclosure, although a separate common voltage line and aseparate output line are not disposed, a common voltage can be suppliedto a sensor pixel through one common line, and an output current outputfrom the sensor pixel can be sensed.

In the touch sensor and the display device including the same accordingto the present disclosure, the number of lines required to drive thetouch sensor can be decreased.

Example embodiments have been disclosed herein, and although specificterms are employed, they are used and are to be interpreted in a genericand descriptive sense only and not for purpose of limitation. In someinstances, as would be apparent to one of ordinary skill in the art asof the filing of the present application, features, characteristics,and/or elements described in connection with a particular embodiment maybe used singly or in combination with features, characteristics, and/orelements described in connection with other embodiments unless otherwisespecifically indicated. Accordingly, it will be understood by those ofskill in the art that various changes in form and details may be madewithout departing from the spirit and scope of the present disclosure asset forth in the following claims.

What is claimed is:
 1. A touch sensor comprising: a plurality of sensorpixels; a sensor scan driver configured to supply sensor scan signals tothe sensor pixels through sensor scan lines; a power supply unitconfigured to supply common voltages to the sensor pixels through commonlines; and a read-out circuit connected to the sensor pixels through thecommon lines, the read-out circuit configured to sense a touch by usingan output signal output through the common lines, wherein two sensorpixels adjacent to each other among the sensor pixels share one commonline.
 2. The touch sensor of claim 1, wherein one sensor pixel betweenthe two sensor pixels provides the output signal to the read-out circuitduring only a first period in one frame period, and the other sensorpixel between the two sensor pixels provides the output signal to theread-out circuit during only a second period different from the firstperiod in the one frame period.
 3. The touch sensor of claim 1, whereinthe power supply unit alternately provides a first common voltage and asecond common voltage having a level lower than that of the first commonvoltage to each of the common lines for every certain period.
 4. Thetouch sensor of claim 1, wherein the power supply simultaneouslyprovides the common voltages having levels different from each other toodd-numbered common lines and even-numbered common lines among thecommon lines.
 5. The touch sensor of claim 1, wherein a first sensorpixel between the two sensor pixels is connected to a jth (j is anatural number) common line and a (j+1)th common line, and a secondsensor pixel between the two sensor pixels is connected to the (j+1)thcommon line and a (j+2)th common line.
 6. The touch sensor of claim 5,wherein, during a first period in one frame period, the power supplyunit supplies a first common voltage to the jth and (j+2)th commonlines, and supplies a second common voltage having a level lower thanthat of the first common voltage to the (j+1)th common line, andwherein, during a second period in the one frame period, the powersupply unit supplies the second common voltage to the jth and (j+2)thcommon lines, and supplies the first common voltage to the (j+1)thcommon line.
 7. The touch sensor of claim 6, wherein the first periodand the second period do not overlap with each other.
 8. The touchsensor of claim 6, wherein the first sensor pixel provides the outputsignal to the read-out circuit during the first period.
 9. The touchsensor of claim 8, wherein, when the output signal is provided throughthe jth common line, the read-out circuit determines that a touch hasbeen generated on the first sensor pixel.
 10. The touch sensor of claim8, wherein, when the output signal is provided through the (j+1)thcommon line, the read-out circuit determines that any touch has not beengenerated on the first sensor pixel.
 11. The touch sensor of claim 6,wherein the second sensor pixel provides the output signal to theread-out circuit during the second period.
 12. The touch sensor of claim1, wherein a sensor pixel connected to a jth common line, a (j+1)thcommon line, an ith (i is a natural number) sensor scan line, and an(i+1)th sensor scan line among the sensor pixels includes: a sensorelectrode; a first transistor having a gate electrode connected to thesensor electrode, a first electrode connected to a first node, and asecond electrode connected to a second node; a second transistor havinga gate electrode connected to the (i+1)th sensor scan line, a firstelectrode connected to the jth common line, and a second electrodeconnected to the first node; a third transistor having a gate electrodeconnected to the ith sensor scan line, a first electrode connected tothe jth common line, and a second electrode connected to the sensorelectrode; and a fourth transistor having a first electrode connected tothe second node, and a gate electrode and a second electrode, which areconnected to the (j+1)th common line.
 13. The touch sensor of claim 12,wherein the sensor pixel further includes a capacitor electrode thatforms a first capacitor together with the sensor electrode.
 14. Thetouch sensor of claim 12, wherein, when the touch is generated, thesensor electrode forms a second capacitor together with a finger of auser.
 15. The touch sensor of claim 12, wherein, when the sensor scansignal is supplied to the (i+1)th sensor scan line, the sensor pixelprovides the output signal to the read-out circuit.
 16. A touch sensorcomprising: a plurality of sensor pixels; a sensor scan driverconfigured to supply sensor scan signals to the sensor pixels throughsensor scan lines; a power supply unit configured to supply commonvoltages to the sensor pixels through common lines; and a read-outcircuit connected to the sensor pixels through the common lines, theread-out circuit configured to sense a touch by using an output signaloutput through the common lines, wherein a sensor pixel connected to ajth (j is a natural number), a (j+1)th common line, an ith (i is anatural number) sensor scan line, and an (i+1)th sensor scan line amongthe sensor pixels includes: a sensor electrode; a first transistorhaving a gate electrode connected to the sensor electrode, a firstelectrode connected to a first node, and a second electrode connected toa second node; a second transistor having a gate electrode connected tothe (i+1)th sensor scan line, a first electrode connected to the jthcommon line, and a second electrode connected to the first node; a thirdtransistor having a gate electrode connected to the ith sensor scanline, a first electrode connected to the jth common line, and a secondelectrode connected to the sensor electrode; and a fourth transistorhaving a first electrode connected to the second node, and a gateelectrode and a second electrode, which are connected to the (j+1)thcommon line.
 17. The touch sensor of claim 16, wherein the sensor pixelis activated when a first common voltage is supplied to the jth commonline, and a second common voltage having a level lower than that of thefirst common voltage is supplied to the (j+1)th common line, and whereinthe sensor pixel is non-activated when the second common voltage issupplied to the jth common line and, the first common voltage issupplied to the (j+1)th common line.
 18. The touch sensor of claim 17,wherein, when the sensor pixel is activated, and a touch of a user isgenerated on the sensor pixel, the output signal is provided to theread-out circuit through the jth common line via the first, second, andfourth transistors.
 19. The touch sensor of claim 17, wherein, when thesensor pixel is activated, and the touch of a user is not generated onthe sensor pixel, the output signal is provided to the read-out circuitthrough the (j+1)th common line.
 20. A display device comprising:display pixels configured to display an image; a plurality of sensorpixels disposed on the display pixels; a sensor scan driver configuredto supply sensor scan signals to the sensor pixels through sensor scanlines; a power supply unit configured to supply common voltages to thesensor pixels through common lines; and a read-out circuit connected tothe sensor pixels through the common lines, the read-out circuitconfigured to sense a touch by using an output signal output through thecommon lines, wherein two sensor pixels adjacent to each other among thesensor pixels share one common line.